Abstract
Biologic therapy with anti-TNFα agents represents a very effective treatment modality in inflammatory bowel diseases. Secondary loss of response to anti-TNFα treatment is an important problem in clinical practice, possibly caused by low levels of the drug in serum.
Development of anti-drug antibodies may be responsible for low drug levels in some patients. Dose intensification (dose increase and/or shortening of application interval) may restore the primary efficacy in some patients while the others benefit from switch to another anti-TNFα agent.
In some patients, anti-TNFα therapy has to be stopped and the treatment with other mechanism of action is required. Pharmacokinetic monitoring seems to be beneficial in optimisation of anti-TNFα treatment in some patients with loss of response to biologic therapy.